Kayexalate Drug Interactions Require More Studies: FDA

Federal regulators are ordering the manufacturer of the generic drug Kayexalate, a potassium decreasing medication, to conduct new clinical studies to ensure that it does not alter or bind to other medications, potentially decreasing the effects of other drugs.

In a drug safety communication on October 22, the FDA announced that the manufacturer of Kayexalate, Concordia Pharmaceuticals, will conduct further studies to determine if the medication can bind and alter the effect of other oral medications.

Kayexalate is classified as a sodium polystyrene sulfonate and is used to treat patients with high levels of potassium in their blood. The prescription medication is taken orally usually between one and four times per day to allow the body to bind potassium in the large intestine so it can be removed naturally. High levels of potassium in the blood can cause heart rhythm issues.

The FDA demanded the new studies after research found a similar sodium polystyrene sulfonate potassium-lowering drug, Veltassa, altered other medications’ efficacy. The researchers found that Veltassa bound to about half of the prescription medications it was tested with, including prescription blood pressure and blood thinners, and also over-the-counter drugs.

As a result, Valtassa’s manufacturer was forced to change the warning label on the medication to instruct users to not take any other forms of oral medication within six hours of it to avoid disruptions.

The FDA stated that the binding of medications could cause serious adverse health consequences in users, potentially decreasing the effects of other medications. Such interferences could exacerbate and individuals pre-existing heart condition since high potassium levels are known to cause heart rhythm problems.

If the additional studies into Kayexalate result in similar findings showing medication binding, the FDA will require Concordia and all other sodium polystyrene sulfonate manufacturers to update their label warnings as well.

Until the studies are complete, the FDA recommends that Kayexalate patients avoid taking any other oral medications within six hours of their Kayexalate dose. Individuals are not being instructed to stop taking their potassium lowering medications nor any other form of prescribed or over-the-counter medication and should consult with their healthcare provider for further instructions regarding dosage separation.